Polarizer 101

A common question about using polarizing filters is, "Can you turn off polarization?" To better understand how a polarizing filter works, let’s take a quick look at its optical design. A circular polarizer (CP) has two pieces of polarized glass that are pressed together with the polarization film on each lens lying perpendicular to each other. Because of the way that CP filters are built,  you can adjust the level of polarization by simply rotating the filter in front of the camera lens one way or the other until you reach the desired polarization in your scene. 

Most polarizing filters feature an outer adjustment ring that you can move while the filter is attached to your lens.  So, now back to the original question, 'can I really “turn off” polarization on a polarization filter' and the answer would be "no" - a CP will always polarize some light when placed in front of a camera lens. The best you can do is change the strength of polarization in your image by rotating the filter counterclockwise (weaker polarizing effect) or clockwise (stronger polarizing effect) until you achieve the amount of polarization you want. But if you want to “turn off” polarization, just take the CP filter off of your camera lens, and try something like a haze or UV filter instead to provide a little bit of ambient noise reduction as well as adding protection against dust and moisture when shooting outdoors. 

When to use a Polarizer

Use a polarizer filter anytime you want to reduce the amount of reflected light in your scene. Polarizer filters are useful around water especially, helping to cut down the glare coming off of the water’s surface, and as a result brings out more detail in highlighted and shadow areas of a scene. 

There may be times where you want to keep some reflections that are working for your composition. For example, you may want to capture the reflection of a group of buildings or trees on the surface of a lake to create an image that highlights this symmetry. If you were to use a polarizer in this instance, you would reduce the reflection on the water’s surface, and the symmetry in the image would not be as strong, if not completely negated. 

Also, keep in mind when shooting that a polarizing filter reduces the amount of light entering your camera lens by about 1.5 - 2 stops, depending on how the filter is adjusted.

Final Thoughts

A Circular Polarizer filter is an essential tool that belongs in every photographer’s kit, new or seasoned, providing glare reduction and bringing out details in highlighted and shadowed areas that isn’t possible in post processing, giving an image a broader overall dynamic range. They are easy to use, and often can be the difference between a professional looking landscape photo (or video) and an amateur composition. 

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